1. Field of the Invention
The present invention relates generally to a multi-band antenna, and more particularly to a multi-band antenna with single feeding point and multi radiating portions.
2. Description of the Prior Art
A present electric device always needs multi antennas for wireless communication. And in most designs, theses antennas are assembled in the inner space of the electric device. Thus, antennas used on different frequency bands are integrated together to reduce their volume.
U.S. Patent application Publication No. 2007/0040754 discloses an antenna structure integrating a first antenna of wireless wide area network (WWAN) and a second antenna of wireless local area network (WLAN), the same as U.S. Pat. No. 7,289,071, U.S. patent application Publication Nos. 2007/0060222, 2007/0096999, and so on. The two antennas respectively work as a single antenna but not influence to each other. However, some wireless communication criterions have common frequency band. For example, the center frequency under WLAN includes 2.4 GHz and 5 GHz and the frequency band under Worldwide Interoperability for Microwave Access (WiMax) includes 2.3-2.4 GHz, 2.5-2.7 GHz and 3.3-3.8 GHz, which overlaps the frequency bands under WLAN. Accordingly, an antenna integrated with a single WLAN antenna and a single WiMax antenna is not benefit for saving the inner space of the electric device.
Hence, in this art, a multi-band antenna to overcome the above-mentioned disadvantages of the prior art will be described in detail in the following embodiment.